A JSON object will be decoded as a list with a single map value. This
will be properly coerced later, so let it through the initial config
semantic checks.
Terraform 0.7 introduces lists and maps as first-class values for
variables, in addition to string values which were previously available.
However, there was previously no way to override the default value of a
list or map, and the functionality for overriding specific map keys was
broken.
Using the environment variable method for setting variable values, there
was previously no way to give a variable a value of a list or map. These
now support HCL for individual values - specifying:
TF_VAR_test='["Hello", "World"]'
will set the variable `test` to a two-element list containing "Hello"
and "World". Specifying
TF_VAR_test_map='{"Hello = "World", "Foo" = "bar"}'
will set the variable `test_map` to a two-element map with keys "Hello"
and "Foo", and values "World" and "bar" respectively.
The same logic is applied to `-var` flags, and the file parsed by
`-var-files` ("autoVariables").
Note that care must be taken to not run into shell expansion for `-var-`
flags and environment variables.
We also merge map keys where appropriate. The override syntax has
changed (to be noted in CHANGELOG as a breaking change), so several
tests needed their syntax updating from the old `amis.us-east-1 =
"newValue"` style to `amis = "{ "us-east-1" = "newValue"}"` style as
defined in TF-002.
In order to continue supporting the `-var "foo=bar"` type of variable
flag (which is not valid HCL), a special case error is checked after HCL
parsing fails, and the old code path runs instead.
This is the first step in allowing overrides of map and list variables.
We convert Context.variables to map[string]interface{} from
map[string]string and fix up all the call sites.
